Non-volatile memory devices are used in any application that requires the storing of information binary data (or bits) that should be maintained even when the memory devices are not powered. Each non-volatile memory device typically comprises a matrix of memory cells, and peripheral circuits to perform management and access functions, for example, reading circuits comprising sense amplifiers to perform reading operations of selected memory cells.
During a reading operation, each sense amplifier is configured to compare electrical signals through (one or more) selected memory cells to appropriate reference values, and to determine the information bits stored therein according to such comparison. As should be known, the reduced extent of such electrical signals and the presence of capacitive components having high values require a reading operation with different operating phases of the sense amplifier (for example, discharge, pre-charge, equalization, and latch), each one being enabled/disabled by a corresponding phase signal.
The present inventor has observed that such phase signals, generated by a signals generation block, result in some drawbacks that affect the performance of the non-volatile memory device. In fact, the relatively high number of phase signals (typically four or more) needed to control the sense amplifier during the reading operation makes the design of the signals generation block critical, both in terms of performance (as it is necessary to ensure that all phase signals have appropriate speed and accuracy), and in terms of area occupation.
Furthermore, a high number of phase signals requires long times for the configuration (i.e., for setting the corresponding timings) and for the test (as they have to be configured and tested one by one). This determines an increase of the production costs of the non-volatile memory device, and a greater likelihood of introducing errors (during the configuration and/or the test).
The inventor has also noticed that the non-volatile memory devices have limitations in low supply voltages conditions. In fact, to achieve reduced access times and reduced area occupation, the sense amplifiers are typically designed to operate with low supply voltages (typically 1.2-1.8 V). However, as should be known, the supply voltage can reach (in the presence of noise and/or unwanted fluctuations) excessively low values (e.g., lower than 1V). This results in an incorrect operation of the sense amplifiers, and thus errors in the reading operation.
It is noted that known approaches (such as those described in U.S. Pat. No. 7,272,062 and U.S. Pat. No. 7,508,716) may not completely address the cited problems.